###
  # build: Generic definitions
  #
  #  Lots of this code have been borrowed or heavily inspired from parts
  #  of kbuild code, which is not credited, but mostly developed by:
  #
  #  Copyright (C) Sam Ravnborg <sam@mars.ravnborg.org>, 2015
  #  Copyright (C) Linus Torvalds <torvalds@linux-foundation.org>, 2015
  #
  
  ###
  # Convenient variables
  comma   := ,
  squote  := '

  pound   := \#

  
  ###
  # Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
  dot-target = $(dir $@).$(notdir $@)
  
  ###
  # filename of target with directory and extension stripped
  basetarget = $(basename $(notdir $@))
  
  ###
  # The temporary file to save gcc -MD generated dependencies must not
  # contain a comma
  depfile = $(subst $(comma),_,$(dot-target).d)
  
  ###
  # Check if both arguments has same arguments. Result is empty string if equal.
  arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \
                      $(filter-out $(cmd_$@),   $(cmd_$(1))) )
  
  ###
  # Escape single quote for use in echo statements
  escsq = $(subst $(squote),'\$(squote)',$1)
  
  # Echo command
  # Short version is used, if $(quiet) equals `quiet_', otherwise full one.
  echo-cmd = $(if $($(quiet)cmd_$(1)),\
             echo '  $(call escsq,$($(quiet)cmd_$(1)))';)
  
  ###
  # Replace >$< with >$$< to preserve $ when reloading the .cmd file
  # (needed for make)

  # Replace >#< with >$(pound)< to avoid starting a comment in the .cmd file

  # (needed for make)
  # Replace >'< with >'\''< to be able to enclose the whole string in '...'
  # (needed for the shell)

  make-cmd = $(call escsq,$(subst $(pound),$$(pound),$(subst $$,$$$$,$(cmd_$(1)))))

  
  ###
  # Find any prerequisites that is newer than target or that does not exist.
  # PHONY targets skipped in both cases.
  any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^)
  
  ###

  # Copy dependency data into .cmd file
  #  - gcc -M dependency info
  #  - command line to create object 'cmd_object :='

  dep-cmd = $(if $(wildcard $(fixdep)),                                           \
             $(fixdep) $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;           \
             rm -f $(depfile);                                                    \
             mv -f $(dot-target).tmp $(dot-target).cmd,                           \

             printf '$(pound) cannot find fixdep (%s)
  ' $(fixdep) > $(dot-target).cmd; \
             printf '$(pound) using basic dep data
  
  ' >> $(dot-target).cmd;           \

             cat $(depfile) >> $(dot-target).cmd;                                 \

             printf '
  %s
  ' 'cmd_$@ := $(make-cmd)' >> $(dot-target).cmd)

  
  ###

  # if_changed_dep  - execute command if any prerequisite is newer than
  #                   target, or command line has changed and update
  #                   dependencies in the cmd file
  if_changed_dep = $(if $(strip $(any-prereq) $(arg-check)),         \

                    @set -e;                                         \

                    $(echo-cmd) $(cmd_$(1));                         \
                    $(dep-cmd))

  
  # if_changed      - execute command if any prerequisite is newer than
  #                   target, or command line has changed

  if_changed = $(if $(strip $(any-prereq) $(arg-check)),                   \
                @set -e;                                                   \
                $(echo-cmd) $(cmd_$(1));                                   \
                printf '%s
  ' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd)

  
  ###
  # C flags to be used in rule definitions, includes:
  # - depfile generation
  # - global $(CFLAGS)
  # - per target C flags
  # - per object C flags
  # - BUILD_STR macro to allow '-D"$(variable)"' constructs

  c_flags_1 = -Wp,-MD,$(depfile) -Wp,-MT,$@ $(CFLAGS) -D"BUILD_STR(s)=\#s" $(CFLAGS_$(basetarget).o) $(CFLAGS_$(obj))

  c_flags_2 = $(filter-out $(CFLAGS_REMOVE_$(basetarget).o), $(c_flags_1))
  c_flags   = $(filter-out $(CFLAGS_REMOVE_$(obj)), $(c_flags_2))

  cxx_flags = -Wp,-MD,$(depfile) -Wp,-MT,$@ $(CXXFLAGS) -D"BUILD_STR(s)=\#s" $(CXXFLAGS_$(basetarget).o) $(CXXFLAGS_$(obj))

  
  ###
  ## HOSTCC C flags

  host_c_flags = -Wp,-MD,$(depfile) -Wp,-MT,$@ $(KBUILD_HOSTCFLAGS) -D"BUILD_STR(s)=\#s" $(HOSTCFLAGS_$(basetarget).o) $(HOSTCFLAGS_$(obj))